The report analyzes a number of factors, including GDP per capita, life expectancy, and freedom to make life choices, based on surveys from respondents in 156 countries. It then ranks the countries based on their cumulative scores.

Norway ranked highest despite its low oil prices, which has led to a weaker economy. As Bloomberg notes, Norway relies on gas and oil for about one-fifth of its economic output, and the petroleum industry cut nearly 30,000 jobs in 2016. Still, the country is resilient.

"By choosing to produce its oil slowly, and investing the proceeds for the future rather than spending them in the present, Norway has insulated itself from the boom and bust cycle of many other resource-rich economies," it reads. "To do this successfully requires high levels of mutual trust, shared purpose, generosity and good governance, all factors that help to keep Norway and other top countries where they are in the happiness rankings."

Not to mention, Norwegians on average have a high life expectancy (80 years), enjoy a large GDP ($62,025 per capita), and experience relatively low levels of political corruption.

Public education is also free in Norway, and 32% of the population has experienced higher education. The country has one of the highest adult literacy rates in the world, too.

For those reasons, the ranking doesn't come as much of a surprise. Norway jumped from #4 in 2016's report to first place this year, followed by Denmark, Iceland, and Switzerland. The country also topped the UN's 2016 Human Development Report, which noted its high levels of education opportunity, financial wealth, and sense of security.

That's not as true for the United States, which has fallen 14 places in the World Happiness Report over the last decade. The report's editors attribute this to multiple causes, including less perceived personal freedom, lower social support, and higher corruption from governments and businesses.